The present invention relates to a resin sheet containing dispersed particles which comprises a base layer containing an inorganic oxide dispersed therein, is thin and lightweight, and is excellent in mechanical strength and dimensional stability. The invention further relates to a resin sheet containing dispersed particles which comprises a base layer containing a diffuser dispersed therein, is thin and lightweight, and is excellent in mechanical strength and light-diffusing properties. The invention furthermore relates to resin sheets which comprise either of those resin sheets containing dispersed particles and a reflecting layer, inorganic gas barrier layer, and color filter layer respectively superposed thereon. The invention still further relates to liquid crystal displays respectively employing those resin sheets containing dispersed particles.
With the trend toward size increase in liquid crystal displays and electroluminescent displays, a resin sheet made of an epoxy resin or the like for use as a substrate has been proposed and developed for the purposes of thickness and weight reduction, etc., because glass substrates are heavy and bulky. However, since the resin sheet not only expands thermally but undergoes expansion and contraction due to the absorption and desorption of water vapor, it has posed a problem that positioning errors occur at the time of electrode formation or color filter formation. In particular, in forming a color filter, it is necessary to form R (red), G (green), and B (blue) patterns and a BM (black matrix) precisely in respective given positions. It has, however, been difficult with the resin sheet to increase the accuracy thereof. Known examples of methods for forming a color filter include: the dyeing process in which dyeable media formed by photolithography are dyed; the pigment dispersion process in which pigmented photosensitive compositions are used; the electrodeposition method in which a patterned electrode is used; the printing method, which is a low-cost process; and the ink-jet method in which colored areas are formed with ink-jet apparatus.
In the field of displays such as liquid crystal displays, a technique has been known which comprises applying a light diffusing sheet containing transparent particles to the viewing side of a liquid crystal cell to prevent the glitter attributable to illumination or the built-in backlight and thereby improve visibility. However, from the standpoint of reducing the thickness and weight of liquid crystal displays, investigations are being made on the impartation of a light diffusing function to a substrate for liquid crystal cells in place of the application of a light diffusion sheet to the viewing side of a liquid crystal cell.
Recently, the demand for small, portable communication terminal apparatus is increasing with the progress in satellite communication and in the technology of mobile communication. The displays mounted on many of such small, portable communication terminal apparatus are required to be thin, and the most frequently used of such displays are liquid crystal displays.
The displays for use in small, portable communication terminal apparatus are further required to be reduced in power consumption and be highly visible when externally illuminated. Because of this, reflection type liquid crystal displays are more frequently used than transmission type liquid crystal displays.
Use of the resin sheet made of an epoxy resin or the like as a substrate for liquid crystal cells has aroused other problems because the resin sheet has poor gas barrier properties. Specifically, one problem is that water vapor and oxygen permeate through the substrate of the liquid crystal cell and enter the cell to cause the transparent conductive film pattern to peel off the substrate. Another problem is that the water vapor and oxygen which have entered the cell accumulate to form bubbles and thereby arouse troubles such as appearance failures and alteration of the liquid crystal.
Accordingly, one object of the invention is to provide a resin sheet containing dispersed particles, which has excellent dimensional stability, and a resin sheet containing dispersed particles, which has excellent light diffusion properties, by using a base layer containing particles dispersed therein
Another object of the invention is to provide resin sheets which comprise either of the resin sheets containing dispersed particles described above, a reflecting layer, inorganic gas barrier layer and color filter layer, respectively superposed thereon.
Still another object of the invention is to provide liquid crystal displays respectively using those resin sheets containing dispersed particles.
The invention provides a resin sheet containing dispersed particles which comprises a base layer comprising a thermoplastic resin or a thermosetting resin, and dispersed therein an inorganic oxide having an average particle diameter of 1 to 100 nm, the amount of the inorganic oxide being 0.1 to 23% by weight based on weight of the base layer.
The resin sheet containing dispersed particles of the invention preferably has a light transmittance of 88% or higher at xcex=550 nm. The resin sheet containing dispersed particles of the invention preferably has a coefficient of linear expansion of 1.00E-4/xc2x0 C. or lower as measured in the temperature range of 100xc2x0 C. to 160xc2x0 C. Furthermore, the dimensional change of the resin sheet containing dispersed particles of the invention as calculated from the size thereof measured immediately after 20 minutes heating at 150xc2x0 C. and the size thereof measured immediately after 20 minutes heating at 150xc2x0 C. and subsequent 2 hour standing at room temperature is preferably lower than +0.020%. An electrode-bearing resin sheet can be produced by forming an electrode on the resin sheet of the invention. A reflection type resin sheet can also be produced by forming a reflecting layer comprising a thin metal layer on the resin sheet containing dispersed particles of the invention. The reflection type resin sheet preferably has an oxygen permeability of 0.3 cc/m2xc2x724 hxc2x7atm or lower.
The invention further provides a liquid crystal display which uses the resin sheet containing dispersed particles which comprises a base layer comprising a resin and an inorganic oxide dispersed therein.
The invention still further provides the resin sheet containing dispersed particles described above wherein the base layer containing an inorganic oxide dispersed therein contains a diffuser dispersed therein which has a refractive index different from that of the resin constituting the base layer and has an average particle diameter of 0.2 to 100 xcexcm, the amount of the diffuser being 0.1 to 60% by weight based on the weight of the base layer. The difference in specific gravity between the diffuser and the resin constituting the base layer is preferably 1 or smaller, and the difference in refractive index between the diffuser and the resin constituting the base layer is preferably 0.03 to 0.10. A reflecting layer comprising a thin metal layer may be formed on the resin sheet containing dispersed particles. This resin sheet containing dispersed particles which has a reflecting layer preferably has an oxygen permeability of 0.3 cc/m2xc2x724 hxc2x7atm or lower. In the resin sheet containing dispersed particles described above wherein the base layer contains both an inorganic oxide and a diffuser and is an outermost layer, this outermost layer is preferably smooth. The invention can further provide a liquid crystal display which uses the resin sheet containing dispersed particles in which the base layer contains both an inorganic oxide and a diffuser.
The invention furthermore provides a resin sheet containing dispersed particles which comprises a base layer which is constituted of a thermoplastic resin or thermoset resin and contains, dispersed in the resin, a diffuser which has a refractive index different from that of the resin and has an average particle diameter of 0.2 to 100 xcexcm, the amount of the diffuser being 200 parts by weight or smaller per 100 parts by weight of the resin constituting the base layer. The difference in specific gravity between the diffuser and the resin constituting the base layer is preferably 1 or smaller, and the difference in refractive index between the diffuser and the resin constituting the base layer is preferably 0.03 to 0.10. A reflection type resin sheet can be produced by forming a reflecting layer comprising a thin metal layer on the resin sheet containing dispersed particles wherein the base layer contains a diffuser. This reflection type resin sheet preferably has an oxygen permeability of 0.3 cc/m2xc2x724 hxc2x7atm or lower.
The invention furthermore provides a resin sheet containing dispersed particles which comprises a base layer comprising a thermoplastic resin or thermoset resin and dispersed therein an inorganic oxide having an average particle diameter of 1 to 100 nm and an inorganic gas barrier layer, the amount of the inorganic oxide being 0.1 to 23% by weight based on the weight of the base layer. This resin sheet containing dispersed particles of the invention, which comprises a base layer comprising a resin and an inorganic oxide dispersed therein and an inorganic gas barrier layer, preferably has a light transmittance of 85% or higher at xcex=550 nm. This resin sheet containing dispersed particles preferably has a coefficient of linear expansion of 1.00E-4/xc2x0 C. or lower as measured in the temperature range of 100xc2x0 C. to 160xc2x0 C. The dimensional change of the resin sheet as calculated from the size thereof measured immediately after 20 minutes heating at 150xc2x0 C. and the size thereof measured immediately after 20 minutes heating at 150xc2x0 C. and subsequent 2 hours standing at room temperature is preferably lower than +0.015%. In this resin sheet, the inorganic gas barrier layer is preferably made of a silicon oxide and the ratio of the number of oxygen atoms to that of silicon atoms is preferably 1.5 to 2.0. Alternatively, the inorganic gas barrier layer is preferably made of a silicon nitride and the ratio of the number of nitrogen atoms to that of silicon atoms is preferably 1.0 to 4/3. The inorganic gas barrier layer preferably has a thickness of 5 to 200 nm. This resin sheet containing dispersed particles of the invention, which comprises a base layer comprising a resin and an inorganic oxide dispersed therein and an inorganic gas barrier layer, preferably has a water vapor permeability of 10 g/m2xc2x724 hxc2x7atm or lower.
The invention furthermore provides the resin sheet containing dispersed particles described above wherein the base layer containing an inorganic oxide dispersed therein contains a diffuser dispersed therein which has a refractive index different from that of the resin constituting the base layer and has an average particle diameter of 0.2 to 100 xcexcm, the amount of the diffuser being 0.1 to 60% by weight based on the weight of the base layer. The difference in specific gravity between the diffuser and the resin constituting the base layer is preferably 1 or smaller, and the difference in refractive index between the diffuser and the resin constituting the base layer is preferably 0.03 to 0.10. In the resin sheet containing dispersed particles described above wherein the base layer contains both an inorganic oxide and a diffuser and is an outermost layer, this outermost layer is preferably smooth. The invention can further provide a liquid crystal display which uses the resin sheet containing dispersed particles in which the base layer contains both an inorganic oxide and a diffuser.
The invention furthermore provides a resin sheet containing dispersed particles which comprises: a base layer which is constituted of a thermoplastic resin or thermoset resin and contains, dispersed in the resin, a diffuser which has a refractive index different from that of the resin and has an average particle diameter of 0.2 to 100 xcexcm; and an inorganic gas barrier layer, the amount of the diffuser being 200 parts by weight or smaller per 100 parts by weight of the resin constituting the base layer. The difference in specific gravity between the diffuser and the resin constituting the base layer is preferably 1 or smaller, and the difference in refractive index between the diffuser and the resin constituting the base layer is preferably 0.03 to 0.10. This resin sheet containing dispersed particles preferably has a water vapor permeability of 10 g/m2xc2x724 hxc2x7atm or lower.
The invention furthermore provides a resin sheet containing dispersed particles which comprises a base layer comprising a thermoplastic resin or thermo set resin and dispersed therein an inorganic oxide having an average particle diameter of 1 to 100 nm and a color filter layer, the amount of the inorganic oxide being 0.1 to 23% by weight based on the weight of the base layer. This resin sheet containing dispersed particles of the invention, which comprises a base layer comprising a resin and an inorganic oxide dispersed therein and a color filter layer, preferably has a coefficient of linear expansion of 1.00E-4/xc2x0 C. or lower as measured in the temperature range of 100xc2x0 C. to 160xc2x0 C. The dimensional change of the resin sheet as calculated from the size thereof measured immediately after 20 minutes heating at 150xc2x0 C. and the size thereof measured immediately after 20 minutes heating at 150xc2x0 C. and subsequent 2 hours standing at room temperature is preferably lower than +0.020%.
The invention furthermore provides the resin sheet containing dispersed particles described above wherein the base layer containing an inorganic oxide dispersed therein contains a diffuser dispersed therein which has a refractive index different from that of the resin constituting the base layer and has an average particle diameter of 0.2 to 100 xcexcm, the amount of the diffuser being 0.1 to 60% by weight based on the weight of the base layer. The difference in specific gravity between the diffuser and the resin constituting the base layer is preferably 1 or smaller, and the difference in refractive index between the diffuser and the resin constituting the base layer is preferably 0.03 to 0.10. In the resin sheet containing dispersed particles described above wherein the base layer contains both an inorganic oxide and a diffuser and is an outermost layer, this outermost layer is preferably smooth. The invention can further provide a liquid crystal display which employs the resin sheet containing dispersed particles in which the base layer contains both an inorganic oxide and a diffuser.
The invention furthermore provides a resin sheet containing dispersed particles which comprises: a base layer which is constituted of a thermoplastic resin or thermoset resin and contains, dispersed in the resin, a diffuser which has a refractive index different from that of the resin and has an average particle diameter of 0.2 to 100 xcexcm; and a color filter layer, the amount of the diffuser being 200 parts by weight or smaller per 100 parts by weight of the resin constituting the base layer. The difference in specific gravity between the diffuser and the resin constituting the base layer is preferably 1 or smaller, and the difference in refractive index between the diffuser and the resin constituting the base layer is preferably 0.03 to 0.10.